Gartner's Data Center Networking Magic Quadrant takes on the difficult task of analyzing an extremely fragmented industry, but the study draws one very solid conclusion: Cisco and VMware are at war over influence in the data center -- and SDN is their weapon of choice.
Increasingly, the networking industry is lining up on two sides of a philosophical divide. Cisco favors a data center SDN technology based on vertically integrated hardware with some software on top, and VMware espouses a vertically integrated software stack with just about anyone's hardware underneath. If either company wins this war, they will shape how data center networks evolve.
"Ultimately for enterprises, there are going to be two options for the near future: [VMware] NSX with an Ethernet Fabric vendor or [Cisco] ACI," said Brandon Mangold, network architect for United Airlines.
Gartner's Magic Quadrant declined to identify a market leader for the second year in a row. Instead, Cisco and VMware stand out as the two most influential vendors -- in part because of their SDN strategies. Gartner has classified Cisco, with its Application Centric Infrastructure (ACI), as the only challenger in the market with the go-to-market muscle to sell enterprises on its ideas. The firm identified VMware, with its NSX overlay network software, as the leading visionary. It has the technology that enterprises can deploy today to solve operational challenges in their data center, but it doesn't yet have enough influence over data center networking decision makers.
"It's clear we have two giants not so much fighting for revenue, because there is not much overlap here. One sells hardware and one sells software. The fight here is for influence. If you choose to be strategically aligned with VMware or Cisco ACI, ultimately that's going to lessen the influence of the other player," said Mark Fabbi, vice president and lead author of Gartner's Data Center Networking Magic Quadrant.
Enterprises that adopt the NSX overlay will want physical network infrastructure from a vendor that partners closely with VMware. "When it comes to refreshing that physical network at some point, you will first listen to VMware and get input from them. 'What would you [VMware] like to see in here?'" Fabbi said.
Meanwhile, Cisco wants to keep as much value in its hardware stack as possible because it believes in innovating through hardware, and hardware-based value justifies the high prices it charges for switches. But Cisco also wants to use ACI to extend its influence further up the stack.
"Cisco will try to lead you away from the virtual orchestration systems like vCenter and vCloud and more toward an OpenStack-type solution. They will try to pull your overall orchestration and provisioning system in a different direction. It's this long-term battle for who has the most influence over the data center orchestration because this is really about expanding the pie for both these vendors," Fabbi said.
VMware's vision: Abstract hardware from software
A VMware NSX overlay creates an abstraction layer between the physical network and the applications and services that run over it. This decoupling through abstraction is meant to accelerate innovation.
"The history of computer science is all about layers of abstraction. Those insertions of a layer of abstraction enables the thing below and the thing above to innovate at a native pace," said Chris King, vice president of marketing for VMware. "People said that the compute market would stagnate and no longer innovate when server virtualization took over. Well that wasn't true. Intel and the server manufacturers were able to innovate in a way that was much more meaningful to customers. They could focus on price and performance without having to worry about what was sitting on top."
NSX will allow network vendors to innovate independently at the application layer of a network and free up network operations so they don't have to deal with the barrage of move, add and change requests that hypervisor admins throw at them constantly.
"The [NSX] abstraction layer enables rapid innovation in the underlay and the overlay," King said. "Now does that innovation come without having to change things on the vendor side? No. There is a recast of the value those folks can bring. You saw that in the server side."
Although the majority of data center networking vendors have their own strategies for dealing with network virtualization and SDN, most of them have aligned with VMware NSX to some extent, particularly by adding VXLAN gateway functionality to top-of-rack switches. Juniper Networks has even added VXLAN routing.
"We've found interesting ways to integrate into [our partners'] infrastructure for the purposes of visibility, QoS [quality of service] and prioritization," King said.
Cisco's vision: No abstraction layer
In some ways, Cisco takes the opposite approach to VMware. With ACI, the physical network is fully aware of every application workload traversing it, and policies for those workloads are coordinated by Cisco's APIC controller. Cisco has built two new series of switches -- the Nexus 9300 and Nexus 9500 -- with the requisite engineering needed to implement this application-aware fabric.
Cisco said enterprises shouldn't abstract the intelligence of the network into a separate software layer like VMware NSX. Instead, all of that should be consolidated into a hardware stack that is easier to manage and maintain.
"When you have two of anything it's going to be more expensive to operationalize it," said Soni Jiandani, senior vice president at Cisco. "And there is nothing that can be done architecturally by anyone in the world to close the visibility gap of operations when you have decoupled the overlay and physical infrastructure, which is what first-generation SDN models do, including VMware NSX."
ACI's vertically integrated stack can also encompass all workloads in a data center, she said. VMware NSX relies on VXLAN gateways from switching partners to incorporate bare-metal workloads. ACI does it natively. She said this is an important distinction because server virtualization is not conquering the whole data center. Most workloads are being virtualized, but those that remain bare-metal have physical servers all to themselves. Those workloads have a large physical footprint that overlays need to incorporate.
"While 60% to 70% of workloads are getting virtualized, only 37% of all x86 servers will be virtualized," Jiandani said, citing projections made by IDC for 2017. "I think the world is physical and virtual."
Editor's note: In part two of this story, learn why users have doubts about both Cisco, VMware strategies.